Throttle sticking open

[alinton]

I'm still getting this problem. On acceleration, when I come off the pedal the revs stay up at about 2000 revs for a couple of seconds, then drop down as normal.

Its annoying as the engine often races when I depress the clutch because of this.

Its not the throttle cable; I also tried realigning the butterflies as instructed to last week, but no change.

Its difficult to see which bank is causing it, even with the bar between the two removed, as it doesn't seem to do it nearly as much when the car is stationary - i.e. off load.

Any ideas please what else I can do to tie this down?

Thanks

Andy.

Edited by alinton on Friday 15th June 07:13

[touching cloth]

I'm no expert but I had something similar recently, started as an idle that raced for a bit before settling - then eventually I ended up with an idle at 2k, was a dodgy lambda sensor on mine so worth a look. Believe the software will show it all up but not really up to speed with that either.

That's my tuppence anyway

[trackcar]

you can work out if its a throttle prob or not .. run teh software out on a drive and look at the throttle pot numbers as you let off the throtle .. if the engine races and the pot values are more than they would normally be at idle then the throtle is defo sticking open .. if the engine races but the throtle pots are at idle values when it does it then they have actually closed and you're looking for things like air leaks ie a non throttle link problem. might narrow your search down a bit.

[alinton]

Thanks, if you recall Joo I've got a new type ECU which I don't think has a serial port! (Remember when I was with you we swapped in a different ECU?

So next question, how do I connect the pc?

Thanks


A.

[thegreengoblet]

Mine did something similar a while ago.
Revs holding for a second when pressing the clutch pedal and then slowly going down. Throttle cable and return spring all ok.
It took 3 visits to my Indie, including 2 Throttle Pots changes and a Butterfly valve adjustment before they found the offending part. The butterfly valve return spring inside the rocker. There's one for each bank. Basically had snapped and so the butterfly valaves were not shutting off completely. The funny thing was that everytime they tried something, she was ok for a short while.
But then it would return and it always seemed to be worse when running really hot?
Anyway, after a week or so, they managed to source a new spring from TVR Power - cost about £7 which was a lot cheaper than the 3 visits to the garage beforehand!

[alinton]

Sounds promising, where exactly is that spring please?

Thanks

A.

[thegreengoblet]

alinton said:

Sounds promising, where exactly is that spring please?

Thanks

A.

I wasn't there at the Indie when they found it, but I believe it sits at the oposite end to the Throttle Pot - so at the back of the engine. The spring is linked somehow to the throttle pot rod (which operates the butterfly valves and runs the length of the rocker). The spring is a torsion spring pretty small - about the diameter of your little finger - with 5 or so coils. I think mine went following a right foot dump to floor. So if you've been doing this (or done this recently), then it may be the cause. It was the first - and last - time I've done it. I've reverted back to smooth throttle action!

Bill

[alinton]

Yes I've seen those springs. I guess it could be that, even though I've got another spring pulling the throttle rod towards the nearside airbox.

I wonder how they come off. I guess if one is broken it could be jamming the throttle open a little.

Thanks for the idea!

A.

[thegreengoblet]

alinton said:

Yes I've seen those springs. I guess it could be that, even though I've got another spring pulling the throttle rod towards the nearside airbox.

I wonder how they come off. I guess if one is broken it could be jamming the throttle open a little.

Thanks for the idea!

A.

Reading between the lines of what the Indie told me and seeing the broken spring, I guessed that spring had jammed and that they actually broke it trying to get it out. It is quite a tough little spring. I was worried for a week or so because they couldn't source the Spring - TVR Power had just taken delivery of the containers from TVR and had to sort them which could take weeks and weeks - so I was told. Luckily I got the spring in about a week.

Anyway, hope it helps and you get sorted soon.